Currently I am using arduino to communicate with BLE module. I am successful in entering AT mode and also changing parameters of BLE. However I am unable to pair with my android device (android version-6.0.1). While pairing it says "pairing rejected by BLE-USR-100". Are there any specific configuration which need to set for BLE?

I would also like to program BLE such that when the BLE receive a specific character from a user device (server- mobile application), BLE should pull one of the GPIO pins to LOW state. I am newbie to BLE programming. Please guide me from where do I start. Is there any specific example code available?

The EZ-Serial firmware application that Bob mentioned is a relatively new offering from Cypress, and it functions in some similar ways and has additional features relative to the USR IOT offering. However, it is only available at this time on CYBLE modules, not bare PSoC 4 BLE and PRoC BLE chipsets. You can find details about this firmware platform here:

Just note that this is not the same firmware that you have. Your questions here relate to a platform that is created and supported outside of Cypress. For support with the USR IOT device and platform, I would recommend that you use their support resources: